These studies utilize the techniques of quantitative autoradiography, in situ histochemistry and immunocytochemistry to explore the distribution, regulation and cellular expression of dopamine receptors in human and nonhuman brain. These same techniques are applied to post-mortem brains derived from patients diagnosed with neuropsychiatric or neurodegenerative disorders to determine the role of altered receptor function in the behavioral disturbances associated with Parkinson's disease, Alzheimer's disease and schizophrenia. In collaboration with researchers at other institutes, we are also exploring how dopamine receptors are regulated following damage to the dopamine system in primates and nonprimate species that are administered MPTP to model parkinsonsim.